1. Field of the Invention
The present invention relates to a method of molding a hollow component by welding a plurality of division members and a hollow component molded by the molding method.
2. Description of the Related Art
A conventional method of molding a hollow component is disclosed in Japanese Examined Patent Publication (Kokai) No. 7-75870 (Reference 1). In this conventional molding method, a plurality of division members of a prospective hollow component are molded independently of each other and brought into contact with each other in a mold. A molten resin is injected and filled in the resin path along the peripheral edge of each of the contact parts, and the division members are welded with each other through the filled resin, thereby molding a hollow component.
The surface of each division member formed with the resin path is uneven in the direction at right angles to the length of the resin path, so that the resin path is curved longitudinally. As a result, the weld joint area is increased for an improved welding strength between the division members.
In the prior art described above, however, in spite of the fact that the overall welding strength of the division members (the total joint welding strengths) can be improved by an increased weld joint area, the problem is posed that sealability cannot be easily secured at the weld parts.
On the surface of the resin path of the division members, protrusions have a comparatively large surface-to-volume ratio of the resin (the ratio of the area in contact with the molten resin to the volume receiving heat from the molten resin) and, therefore, are often high in welding strength, while depressions having a comparatively small surface-to-volume ratio of the resin are often low in welding strength.
In the conventional technique, therefore, there is a defect that the welding strength of the weld parts of the hollow component are liable to change along the length of the resin flow path, thereby making it difficult to secure a steady sealability.